Everything You Need to Know About Essential Oils

I am exhaustedI need to go to sleep this second, I thought. Only it was 7:20 on a weeknight and I had tasks to do and kids to get to bed. I'd recently gotten an essential oil diffuser for our bedroom; I thought it might come in handy for stress relief. Now, though, I reached for revitalizing grapefruit oil. I plopped in a few drops and pressed "on." Minutes later, I felt more awake. It worked! Then my husband walked in. "Ew, what's that smell?" he asked. Uh-oh.

Extracted from plants, flowers and citrus fruits, essential oils are hot: Industry revenue has gone up about 13 percent in five years, according to the market-research firm IbisWorld. The ancient Chinese, Egyptians, Indians and Greeks relied on essential oils as medicine. They're now gaining new ground because of growing evidence of their powers; a review published in the International Journal of Neuroscience concluded that various scents can significantly affect mood, cognition and physiology. Increased openness to complementary and alternative treatments is fueling this boom, says Woodson Merrell, MD, director of integrative medicine at Beth Israel Medical Center in New York City: "Patients like essential oils because they're a remedy that is natural, effective and typically safe."

MORE: Natural Ways to Reduce Stress

Today, nurses in hospitals reach for essential oils to treat everything from nausea to anxiety. And it's not just patients who benefit: In the emergency room at Nashville's Vanderbilt University Medical Center, when diffusers were installed to spread citrus scents, the portion of staffers who reported frequently experiencing work-related stress dropped from 41 percent to 3 percent. In stores, you'll find essential oils in body lotions, shampoos, even household cleaners. Someday they may be tapped for other benefits; findings show that applied essential oils can inhibit growth of tumors and kill potentially deadly bacteria like E. coli.

How aromatherapy works When you sniff an essential oil, your olfactory bulb fires off signals to the limbic system, the part of the brain that controls emotionsthat's how scents affect your mood. Depending on the type of oil used, your blood pressure or heart rate may rise or fall, and your body may release certain hormones.

That said, you have to like an oil for it to have an optimal effect (why my husband wasn't rejuvenated by our grapefruited room). "Besides the physical reaction, a psychological one happens when you smell a scent," notes Adriane Fugh-Berman, MD, associate professor of pharmacology at Georgetown University Medical Center. She recalls dissecting cadavers in medical school, when professors dropped peppermint oil into the formaldehyde to mask the odor. "For years, the smell of peppermint reminded me of dead bodies!" she says. "I still have to buy nonpeppermint toothpaste."

MORE: How Fragrance Can Lift Your Mood

FYII (For Your Inhaling Information) Aromatherapy isn't healthy for everyone. People with asthma should avoid essential oils, says Alan Hirsch, MD, neurological director of the Smell & Taste Treatment and Research Foundation in Chicago, and pregnant women need to check with their doctors first. Never drink an essential oil, even in a small amount, without medical supervision. "Essential oils can be poisonous if you ingest too muchthey could affect your nervous system and cause seizures," Dr. Fugh-Berman cautions. (Hel-lo: They're strong enough to decimate E. coli.)

Also note that essential oils may not mix well with certain drugs. For example, blue chamomile oil can hamper the enzyme that metabolizes some antidepressants. "If you're using patch medication, applying essential oils in the area could cause an interaction," adds Andrea Butje, a clinical aromatherapist who runs the Aromahead Institute, which offers virtual courses.

Next Page: How to find the right oils

[ pagebreak ]The essence of finding good oils Don't buy into claims that an oil is "therapeutic," "clinical" or "premium" gradethey're marketing ploys. "There is no body that oversees the essential oil industry, and there is no seal of approval," says Jade Shutes, a clinical aromatherapist and president of the National Association for Holistic Aromatherapy. Generally, USDA-certified organic oils are best because they're not contaminated with pesticides. Telltale signs of a quality product:

 The label or website description lists the Latin name of the plant from which the oil is derived, which indicates that it's pure (thus offering the most potent payoffs). If the label states only "lavender essential oil," the product could contain filler ingredients.

 A company's oils are different prices. It's far cheaper to extract oil from, say, citrus fruits than from flowers; companies that charge the same for every kind may very well be including synthetic substances.

 The oil comes in a glass container that's amber or dark blue to protect it from oxidation. Keep oils in the fridge to prolong their life.

MORE: Bogus Health Trends That Waste Your Time

Rules for inhaling The best way to disseminate an essential oil: through a little machine. Diffusers (they cost around $30 to $40 each) work fine for simply chillaxingyou fill a small basin with water and plop in a few drops of your chosen essential oil, and a fan emits a scented mist. But for a true therapeutic effect, opt for a nebulizer, which shoots oil particles straight into the air sans water. (Nebulizers are used by clinicians and tend to cost a bit more.)

Whichever device you choose, turn it off within an hour, says aromatherapy expert Robert Tisserand, author of Essential Oil Safety: "There's no need to constantly inhaleyou won't get an additional benefit, and you want to give your body a break or it may react adversely to continued inhalation, resulting in increased heart rate, for example." Also: Diffuse when your husband is out of the house, to avoid an adverse reaction in your marriage.